function Drag(id){
	var _this=this;
	this.disX=0;
	this.disY=0;
	this.oDiv=document.getElementById(id);
	this.oDiv.onmousedown=function(ev){
		_this.fnDown(ev);	
		return false;
	}
};
Drag.prototype.fnDown=function (ev){
		var _this=this;
		var oEvent=ev||event;
		this.disX=oEvent.clientX-this.oDiv.offsetLeft;
		this.disY=oEvent.clientY-this.oDiv.offsetTop;
		document.onmousemove=function(){
			_this.fnMove();	
		}
		document.onmouseup=function(){
			_this.fnUp();	
		}
	};
Drag.prototype.fnMove=function (ev){
	var oEvent=ev||event;
	this.oDiv.style.left=oEvent.clientX-this.disX+'px';
	this.oDiv.style.top=oEvent.clientY-this.disY+'px';	
};	
Drag.prototype.fnUp=function (){
	document.onmousemove=null;
	document.onmouseup=null;	
};
